The present invention relates generally to shielding devices for minimizing electromagnetic interference and susceptibility effects on electrical and electronic devices, and more particularly, to a shielding device that is easily formed to a desired size and shape, and to a method of assembly of the shielding device.
It is highly desirable to provide shielding for electronic components found in radio transmitters, radio receivers, computers and other electronic devices that use circuitry that emits or is susceptible to electromagnetic radiation. It is known that these components can be shielded to reduce undesirable electromagnetic interference and/or susceptibility effects with the use of a conductive shield that reflects or dissipates the electromagnetic charges and fields. Such shielding is generally grounded to allow the offending electrical charges and fields to be dissipated without disrupting the operation of the electronic components enclosed within the shield.
A variety of devices have been utilized for shielding electronic components, but these prior art devices have not been entirely satisfactory since they are generally not adjustable in size or in shape since they usually come pre-assembled in predetermined sizes and shapes.
A variety of known prior art shielding devices for components provided on printed circuit boards are frequently included within the same frame or packaging that supports the component being shielded. In order to minimize the size of the component package, the shields are sometimes arranged close to the components being shielded. This close arrangement impedes effective ventilation of these components.
For example, a known shielding device is disclosed in U.S. Pat. No. 4,433,886 issued on Feb. 28, 1984 to Cassarly et al. The Cassarly et al. patent discloses a connector mounting for integrated circuit chip packages that includes a rectangularly shaped electromagnetic shield that is made from electrically conductive sheet metal. The shield has four uninterrupted side walls, from which extend a plurality of rigid ground contact pins. The shield also includes a snap-on cover member having a saddle-like frame that is hingedly mounted at one end to the connector mounting. The disclosed shield is preformed in specific shapes and sizes, and does not offer an end user the ability to adjust the shape or size of the shield.
Another known protective shield is disclosed in U.S. Pat. No. 4,437,718 issued on Mar. 20, 1984 to Selinko. The Selinko patent discloses a non-hermetically sealed stackable chip carrier package having a metallic protective shield. The shield comprises a flat plate having four legs which extend downwardly to support the plate. The shield is intended to be used within the chip package and is not particularly adaptable to a variety of situations.
Another shielding device is disclosed in U.S. Pat. No. 4,512,618 issued Apr. 23, 1985 to Kumar. The Kumar patent discloses an electromagnetic shield including a pre-formed metal member having a shroud whose shape specifically conforms to a connector that it is intended to shield.
Such prior art shielding devices are generally manufactured in only one or a few different specific sizes that cannot be altered easily by the user. Therefore, if a wide variety of differently sized shields are desired, suppliers and users must maintain in stock a relatively large supply of such electromagnetic shields in many different shapes and sizes.
Accordingly, it is an object of the present invention to provide an electromagnetic shield for a printed circuit board that is easy to store and can be easily made to a desired size and shape. It is therefore, a primary object of this invention to fulfill that need by providing such a shield.
More particularly, it is an object of the present invention to provide an electromagnetic shield that can be stored in a disassembled mode and easily assembled by an end user.
It is another object of the present invention to provide an electromagnetic shield that can be easily assembled into one of a variety of shapes and sizes by an end user.
Yet another object of the present invention is to provide an electromagnetic shield that allows ventilation of the components being shielded.
Still another object of the present invention is to provide an electromagnetic shield having a removable cover and engagement prongs to hold the cover that are designed to maintain uniform contact with the cover.
Still yet another object of the present invention is to provide an electromagnetic shield having a top cover that is easily removable to provide access to the components being shielded therein.
It is yet another object of the present invention to provide an electromagnetic shield that is light-weight, yet structurally stable.
A further object of the present invention is to provide an electromagnetic shield, the walls of which are made from a single strip of material, the dimensions of which can be easily adjusted by an end user.
These and other objects are accomplished by an electromagnetic shielding device in accordance with the present invention. The shielding device includes an electromagnetic shield that is assembled from two primary components.
The walls of the shield are made from a longitudinally extending strip of electrically conductive metal having longitudinally extending parallel edges and first and second ends. A plurality of pins extends substantially perpendicularly from one edge thereof and a plurality of engagement prongs extends from the other edge thereof. The engagement prongs are adapted to retain a metal cover plate on the shield.